1. KHABAROVSK REFINERY HYDROPROCESSING PROJECT NORMAL OPERATION APRIL 29th – MAY 3rd 2013, MADRID, SPAIN TRAINING COURSE

2. 2 NORMAL OPERATION The purpose of this section is to give a general explanation of the main parameters that the operator shall check during normal operation. Process variables, that determine a good operation of the Unit, play a different role depending upon the type of operation.

3. 3 CLAUS SECTION PROCESS VARIABLES NORMAL OPERATION AIR/ACID GAS RATIO TEMPERATURE IN  THERMAL REACTOR  CLAUS REACTORS STEAM PRODUCTION PRESSURE FEEDSTOCK VARIATIONS IN  COMPOSITION  PRESSURE  TEMPERATURE PRESSURE PROFILE NORMAL OPERATION

4. 4 NORMAL OPERATION CLAUS SECTION- MAIN PARAMETERS CORRECT QUANTITY OF DEMI WATER/LP CONDENSATE (0.15 m 3 /h) TO THE AMINE ACID GAS SCRUBBER CORRECT H 2 S/SO 2 RATIO IN THE CLAUS TAIL GAS CORRECT CLAUS REACTORS INLET TEMPERATURE (240 AND 206 °C) CORRECT OPERATION OF PIPING AND EQUIPMENT HEATING SYSTEM CORRECT FLUSHING OF INSTRUMENTS AND EQUIPMENT WITH NITROGEN AND AIR QUALITY OF UTILITIES ACCORDING TO THE DESIGN BASIS CORRECT STEAM PRESSURE AND BLOW-DOWN FLOWRATE IN THE CLAUS WHB AND SULPHUR CONDENSERS LIQUID SULPHUR PRODUCTION (FLOW) FROM EACH HYDRAULIC SEAL SULPHUR DEGASSING SYSTEM OPERATION

5. 5 NORMAL OPERATION CLAUS SECTION OPERATION WITH TWO ZONES IN THERMAL REACTOR SPLIT THE FLOW OF AAG BETWEEN 1 ST AND 2 ND ZONE DURING OPERATION WITH SWS (SINGLE ZONE OPERATION WHEN AAG IS THE ONLY FEED) MONITOR THE TEMPERATURE IN THE FIRST ZONE ESPECIALLY DURING OPERATION WITH SWS (ADIABATIC FLAME TEMPERATURE AROUND 1450°C)

6. 6 TGT SECTION PROCESS VARIABLES NORMAL OPERATION TEMPERATURE IN  HYDROGENATOR REACTOR (INLET AND OUTLET)  QUENCH TOWER OUTLET CLAUS TAIL GAS COMPOSITION H 2 EXCESS FROM QUENCH TOWER (MIN. 2.5% vol.) PROCESS WATER FLOWRATE AND pH TAIL GAS SO 2 CONTENT DOWNSTREAM HYDROGENATION REACTOR NO SO 2 CONTENT IN EFFLUENT GAS FROM QUENCH TOWER ALLOWED IN NORMAL OPERATION WHEN TAIL GAS IS TREATED IN AMINE ABSORBER NORMAL OPERATION

7. 7 REDUCTION REACTOR TEMPERATURE AT SOR: INLET 280°C - OUTLET 310°C AT EOR: INLET 320°C - OUTLET 350°C CLAUS TAIL GAS COMPOSITION INSTRUMENTATION AND LINES PURGING SYSTEM OPERATION BY INERT GAS PIPING AND EQUIPMENT HEATING SYSTEM OPERATION HYDROGEN EXCESS AFTER QUENCH TOWER (MIN. 2.5% vol.) TAIL GAS TEMPERATURE FROM QUENCH TOWER SOUR WATER FROM QUENCH TOWER FLOW RATE AND pH SO 2 CONTENT IN EFFLUENT GAS FROM QUENCH TOWER SOUR WATER FILTERS PRESSURE DROP AMINE SOLUTION IN TGT ABSORBER (10 m 3 /h NORMAL) NORMAL OPERATION TGT SECTION – MAIN PARAMETERS

8. 8 AMINE SECTION PROCESS VARIABLES NORMAL OPERATION LEAN AMINE LOADING LEAN AMINE SOLUTION  CONCENTRATION  TEMPERATURE (LEAN AMINE TO ABSORBER) EFFICIENCY OF LEAN/RICH HEAT EXCHANGER PRESSURE DROPS THROUGH FILTERS NORMAL OPERATION

9. 9 LEAN AMINE LOADING (STEAM / AMINE RATIO IN THE REBOILER) LEAN AMINE SOLUTION QUALITY AND CONCENTRATION (50% BY WT.) TEMPERATURE OF LEAN AMINE SOLUTION SENT TO ABSORBER (42°C MAX.) AMOUNT OF AMINE SENT TO FILTERING SYSTEM PRESSURE DROPS THROUGH FILTERS EFFICIENCY OF LEAN/RICH HEAT EXCHANGER CONCENTRATION AND TEMPERATURE OF ACID GAS FROM REFLUX DRUM NORMAL OPERATION AMINE SECTION – MAIN PARAMETERS

10. 10 INCINERATOR SECTION INCINERATOR FLUE GAS  TEMPERATURE  OXYGEN CONTENT TAIL GAS COMPOSITION INCINERATOR OPERATION PROCESS VARIABLES NORMAL OPERATION

11. 11 NORMAL OPERATION INCINERATOR SECTION- MAIN PARAMETERS INCINERATOR CHAMBER TEMPERATURE (650°C) TO GUARANTEE THERMAL CONVERSION OF SULPHUR COMPOUNDS O 2 CONTENT IN FLUE GAS (2% vol. minimum on wet basis) TAIL GAS COMPOSITION Tail gas fed to the Incinerator comes from TGT Section or directly from Claus Section (in case of TGT by-pass) PIPING HEATING SYSTEM OPERATION

12. 12 AMINE REGENERATION SECTION (ARU) PROCESS VARIABLES NORMAL OPERATION RICH AMINE FLOWRATE TO REGENERATOR DEA SOLUTION  CONCENTRATION  TEMPERATURE REGENERATOR PRESSURE NORMAL OPERATION

13. 13 RICH AMINE FLOWRATE (STEAM / AMINE RATIO IN THE REBOILER) DEA SOLUTION QUALITY AND CONCENTRATION (25% BY WT.) TEMPERATURE OF LEAN DEA SOLUTION SENT TO B.L. (55°C MAX.) AMOUNT OF AMINE SENT TO FILTERING SYSTEM PRESSURE DROPS THROUGH FILTERS EFFICIENCY OF LEAN/RICH HEAT EXCHANGER FLOWRATE OF REFLUX TO THE REGENERATOR NORMAL OPERATION ARU SECTION – MAIN PARAMETERS

14. 14 SOUR WATER STRIPPER SECTION (SWS) PROCESS VARIABLES NORMAL OPERATION SOUR WATER FLOWRATE TO STRIPPER SOUR WATER CHARACTERISTICS  CONCENTRATION OF H 2 S AND NH 3  TEMPERATURE STRIPPER PRESSURE NORMAL OPERATION

15. 15 SOUR WATER FLOWRATE (STEAM FLOWRATE TO REBOILER) POLLUTTANT CONCENTRATION IN THE SOUR WATER STRIPPER PRESSURE / TEMPERATURE EFFICIENCY OF FEED/BOTTOM HEAT EXCHANGER FLOWRATE OF PUMPAROUND TO THE STRIPPER NORMAL OPERATION SWS SECTION – MAIN PARAMETERS

16. 16 ROUTINE OPERATION UTILITIES VERIFY SUITABILITY OF SYSTEMS, OPERATION AND CORRECT VALUES OF OPERATING PARAMETERS FOR: STEAM AND STEAM CONDENSATE SYSTEM OPERATION FUEL GAS MOLECULAR WEIGHT AND NETWORK SYSTEM PIPING AND EQUIPMENT HEATING SYSTEM OPERATION NITROGEN AND INSTRUMENT AIR NETWORK SYSTEM OPERATION BOILER FEED WATER NETWORK SYSTEM OPERATION

17. 17 GENERAL PRECAUTIONS OPERATION ACTIONS Compile daily record book Check instruments for: - Maintenance - Periodic readings to be recorded - Unrealistic values Monitor catalyst activity through bed temperature profiles Avoid sudden temperature changes Control liquid carry-over and content of hydrocarbons and ammonia in feeds Schedule frequency of sampling and analyses Perform periodic laboratory analyses to check proper working of on-line analysers Observe refractory color from burner sight glasses Check burners for flame quality and temperature

18. 18 CORRECTIVE ACTION FOR ABNORMAL CONDITIONS ACID GAS FEED LOAD VARIATION ACID GAS FEED COMPOSITION VARIATION No modifications of the normal operating parameters are necessary during turndown operation for both Claus and TGT sections. Load variations should be as smooth as possible to avoid plant upset and shut-down. Acid gas composition variations can produce a remarkable effect on the plant operation and/or on sulphur recovery efficiency. Hydrocarbons Hydrocarbons have several negative effects on the acid gas; the first is the difficulty in burning hydrocarbons if they are present in massive quantities, the second is the effect of dilution of the process gas with the consequent sulphur efficiency decreasing.

19. 19 A further negative effect is the consumption of combustion air according to the rates described. It is important to note that while the H 2 S combustion requires about 0.5 mol O 2 /mol H 2 S, the minimum combustion (partial oxidation) requirement of hydrocarbons : 1.5 mol O 2 /mol CH 4 2.5 mol O 2 /mol C 2 H 6 3.5 mol O 2 /mol C 3 H 8 4.5 mol O 2 /mol C 4 H 10 CORRECTIVE ACTION FOR ABNORMAL CONDITIONS ACID GAS FEED COMPOSITION VARIATION

20. 20 The maximum tolerance of hydrocarbons for the correct and safe acid gas combustion can be calculated according to the following system: CORRECTIVE ACTION FOR ABNORMAL CONDITIONS CH 4 2 X % CH 4 in the acid gas + C 2 H 6 8 X % C 2 H 6 in the acid gas + C 3 H 8 50 X % C 3 H 8 in the acid gas + C 4 H 10 100 X % C 4 H 10 in the acid gas = ∑ ∑ < % H 2 S in the acid gas ACID GAS FEED COMPOSITION VARIATION

21. 21 If the  resulting from the operation is less then the H 2 S percentage in the acid gas, the hydrocarbons contained in the acid gas can be easily tolerated (note that the Thermal Reactor effluent temperature should be always higher than 1000 °C to ensure the hydrocarbons complete destruction). In case the hydrocarbons content in the acid gas exceeds the tolerance calculated as per the above system, some carbon can be formed during the acid gas combustion with the consequence of catalyst plugging and fouling. CORRECTIVE ACTION FOR ABNORMAL CONDITIONS ACID GAS FEED COMPOSITION VARIATION

22. 22 In addition, note that the carbon formation can also be caused by deficiency air operation, even if the hydrocarbons content in the acid gas is within the tolerance limit. The hydrocarbons contained in the acid gas feedstock is largely acceptable; the presence of C4+ hydrocarbons at concentrations exceeding 0.9% is the limit of acceptability to avoid risks of uncompleted hydrocarbons combustion in the Thermal Reactor. ACID GAS FEED COMPOSITION VARIATION CORRECTIVE ACTION FOR ABNORMAL CONDITIONS

23. 23 Ammonia Ammonia in the acid gas has the negative effect of requiring additional process air for the combustion (0.75 molO 2 /molNH 3 ) and therefore diluting the process gas. Non-destroyed ammonia can form deposits of solid salts (ammonium sulphate, ammonium bisulphate, ammonium sulphides) at the low temperature points of the plant, such as at the sulphur condensers outlets. The maximum molar ratio of ammonia in the fed gas to the Thermal Reactor is: mol NH 3 / (mol NH 3 + mol H 2 S) = 0.25 ACID GAS FEED COMPOSITION VARIATION CORRECTIVE ACTION FOR ABNORMAL CONDITIONS

24. 24 The unit has been designed to treat an acid gas stream (acid gas from amine regeneration and acid gas from SWS) with an NH 3 content of about 35% mol. The crucial operation parameter for the ammonia destruction is the adiabatic flame temperature, which has never to drop below 1420 °C. The unit is provided with a two zones thermal reactor which allows to modify the temperature of combustion of the gas containing ammonia as necessary by by-passing a part of the amine acid gas not containing ammonia to the thermal reactor second zone. Higher is the by-pass, higher shall be the temperature of the first zone. Note that the max allowable by pass has never to exceed the 25% of the quantity of the amine acid gas. ACID GAS FEED COMPOSITION VARIATION CORRECTIVE ACTION FOR ABNORMAL CONDITIONS

25. 25 Carbon Dioxide Carbon dioxide plays the role of diluting process gas and of producing COS and CS 2 during the acid gas combustion. The production rate of COS and CS 2 is proportional to the concentration of CO 2 and hydrocarbons in the feed acid gas. Steam Steam present in the acid gas acts as a diluting agent. Note that the increasing of the rate of the acid gas diluting agents implies, in addition to the sulphur recovery efficiency decreasing, the lowering of the plant capacity due to the inevitable increase of the pressure drops of the system. CORRECTIVE ACTION FOR ABNORMAL CONDITIONS ACID GAS FEED COMPOSITION VARIATION

26. 26 Acid gas fed to SRU is normally free from liquids; it is anyway possible, for upsets of the Amine and SWS units, that some liquid is present (water, amine solution and perhaps hydrocarbons). Amine Acid Gas Scrubber and SWS Acid Gas Separator are provided upstream the combustor burner and all the entrained liquids are separated and transferred outside the SRU battery limits by pumps. In case of impossibility in removing liquids from the acid gas separators, very high-level switches shall shut down the unit. CORRECTIVE ACTION FOR ABNORMAL CONDITIONS ENTRAINED LIQUID

27. 27 The effect of liquid entrained to the burner is to create disturbance to the acid gas flame and the sudden evaporation in the combustion chamber with the risk to damage the Thermal Reactor refractory lining. A long-term effect of entrained liquid (H 2 O) may be also the corrosion of the acid gas piping lines. The amine acid gas and the SWS acid gas lines are traced/jacketed as a protection against condensation of steam and to avoid precipitation of solid salts, which could plug the lines. Tracing/Jacketing facilities shall be maintained in operation in all seasons. ENTRAINED LIQUID CORRECTIVE ACTION FOR ABNORMAL CONDITIONS

28. 28 FUEL GAS Fuel gas pressure much lower than normal shall cause the Incinerator shut ‑ down and consequently the SRU shut ‑ down; this is necessary in order to prevent lack of flame to the Incinerator Burner in case of Fuel gas network failure; a pre ‑ alarm of low and high Fuel gas pressure in control room shall inform the operator. Variation of fuel gas composition has not practical effects on the Incinerator operation, provided that the system operates on automatic control. CORRECTIVE ACTION FOR ABNORMAL CONDITIONS

29. 29 On the other side, fuel gas variations in composition would be quite important for the combustion operation during plant heating up. For this reason it is necessary that any variation of the Fuel gas feed composition is anticipated to the operator, which shall change the combustion parameters accordingly. Note that an incorrect (not stoichiometric) operation during fuel gas combustion, in plant heating up stages could be dangerous due to the possibility of carbon formation (oxygen deficiency) and to the presence of excess oxygen in the flue gas. CORRECTIVE ACTION FOR ABNORMAL CONDITIONS FUEL GAS

30. 30 Low-pressure steam is used to heat all the parts of sulphur plant containing liquid sulphur in order to avoid solidification. All plant components containing liquid sulphur are heated with steam at a temperature not exceeding 160 °C, because at this temperature liquid sulphur starts becoming very viscous. LS steam is used for tracing/heating purposes. The steam heating for “sulphur” services is provided essentially to maintain the sulphur at liquid state or to avoid (or minimize) the condensation of the sulphur at vapour state; it is therefore extremely important that the heating system is always well efficient. We suggest checking the “sulphur” service heating efficiency at least daily. The heating in non ‑ sulphur services is essentially provided in order to avoid water or liquid condensation in vessels or piping lines, so preventing corrosion. CORRECTIVE ACTION FOR ABNORMAL CONDITIONS LP STEAM USES

31. 31 CORRECTIVE ACTION FOR ABNORMAL CONDITIONS DEA FLOW VARIATION SOUR WATER COMPOSITION VARIATION If the amount of products to be absorbed by the amine in the Absorption Section increases, the circulating amine solution flowrate shall increase proportionally and the saturated steam flowrate to the Reboiler shall be increased. If the amount of pollutants (H 2 S and NH 3 ) in the sour water increases, it shall be necessary to increase the pressure (and therefore the temperature) in the Stripper. Hydrocarbons Hydrocarbons cause fouling of the heat exchanger: it can be controlled by checking that the Slop Oil Pump works properly.

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